A conventional apparatus has been known for electrically discriminating a disk such as a coin, which utilizes the fact that a disk dropped in changes a magnetic flux generated by a coil. There have been various kinds of such electronic discriminating apparatuses.
For example, a conventional design employs a discriminating apparatus having a configuration in which a plurality of coin sensors (hereinafter “sensors”), each of which includes a pair of coils attached opposite to each other on the opposite side walls in a thickness direction, are disposed in a path where a disk such as a coin drops due to its own weight. A voltage signal variation of each sensor is detected that is caused by a magnetic flux variation generated by the disk, such as a coin moving in the course of dropping and passing between the coils of each sensor to determine whether the disk is real or not (JP-A-2002-74444 (pp. 3 to 5, FIGS. 1 to 23)). In this case, the sensors at both right and left ends discriminate a size of the coin, namely, determine whether or not the coin has a predetermined diameter, and the sensor at a center detects a material or thickness thereof.
Here, in a case of the discriminating apparatus, the sensors must be disposed on a side wall and the other side wall opposite thereto in the path, respectively, and further, there is some complication during assembly because of a physical limitation that requires sensors to be disposed on a narrow coin path of a coin selector, which consequently poses a problem with assembly accuracy. Particularly, if the center of a coil deviates in position during the sensor assembly, discrimination performance is adversely influenced, and care must be therefore given to the assembly. Such a physical limitation as to a sensor position in space makes it difficult to dispose many sensors, to improve selection accuracy. Further this limits the ability to shrink the size of the apparatus. There is also a problem in which the cost of manufacture, management and the like is high because of parts management issues associated with handling many small sensors.
When a coin is detected by the plurality of coin sensors disposed on the sides of the coin path along a diameter direction of a coin, the sensor positioned at a center of the coin detects a material or thickness of the coin using a peak value of a detection output of the sensor. However, when coins are sequentially dropped in, the coins are lined up end to end and pass through the sensor, so that the sensor is influenced by both preceding and following coins lined up end to end, which results in the appearance of a plurality of peak values in a detection output of the sensor, or sequential appearance of approximate peak values in a detection output. Therefore, in the signal output, there is the difficulty of clearly discriminating preceding and following coins.